The pathogenesis of glucose intolerance in patients taking PI therapy and developing diabetes is not known. The oral glucose tolerance test has been used clinically to screen for diabetes mellitus. We propose to use the oral glucose tolerance test to address the specific aims outlined below: 1. To determine if use of protease inhibitors is associated with glucose intolerance. 2. To determine if acute phase insulin release is appropriate in patients on protease inhibitors. The patient population for this study will be adult men and women with HIV infection, with no prior history of diabetes who are about to initiate antiretroviral therapy using one or more protease inhibitors.